This invention relates generally to valves and more particularly to an internal valve for use in a system for filling and emptying fuel storage tanks and the like.
Fluid storage tanks may be provided with an internal valve which is mounted in an aperture in a lower portion of the housing providing ready access by an operator. A dependable structure, however is required, as the valve may control many thousands of pounds of fuel. Special devices are employed in this regard to assure that damage does not occur to the sealing element in such valve and one such measure is the provision of a soft closure or slow closure of such inlet valve to avoid extremely high closing force transients.
As the fueling operator does not have convenient access to the top of the tank being filled it is typical to have some means for remote actuation of the vent valve located there to avoid either pressure build up or partial vacuum in the tank. The actuation of the vent valve often is automatically combined with actuation of the main inlet valve by means of linkages or the like. Further, special devices have been employed to recognize that the tank has been filled to automatically close the main inlet valve, fluid jet sensors often being used in this regard in either a single or dual arrangement, the latter allowing an intermediate throttled condition of the inlet valve. Still further it is typical that such internal valve is capable of being automatically actuated in response to fluid pressure received at the inlet thereof with closure being provided as described, by the jet sensor derived devices or that the valve be manually actuable by the attendant in fueling or defueling modes.
Prior art embodiments of such forms of internal valve utilizing jet sensor control devices or soft closure for the main valve inlet are shown in U.S. Pat. Nos. 2,775,258, 3,095,894 and 3,174,503.